Bring a cooler, pack it with as much as you possibly can. Eating in restaurants is no bueno.

Eat fresh as much as possible. Eat one GOOD meal a day, walk for excercise, don't eat before you sleep...it interrupts the digestion process. Overeating will slow you down.

light dinners also. biggest meal (but keep it healthy) should be breakfast. Remember if you go to bed at 10PM, with last meal at 6PM, and you wake up at 0600, you have gone 12 hours with no food. The guys who "skip breakfast" are running on fumes mentally and physically when lunch comes around. Not a good idea.

Will airlines allow me to bring perishable food onboard and throw it in the galley's chiller, or do I absolutely need to pack it in my own chiller?

You won't find chillers in most narrowbody aircraft.